The limpet, the sea snake and the duck

Three new technologies are making wave power attractive, both to private investors and government-run utilities.

On the isle of Islay off the coast of Scotland, where standing stones dot the landscape and Gaelic is still heard in pubs, the world’s first working wave-power device has been puttering away for roughly seven years.

The Land Installed Marine Power Transformer (LIMPET), developed by the Scottish firm Wavegen, is the first wavepower station to deliver energy to a national electrical grid. As waves move in and out of the generator, they press against a compression chamber that sits at the shore’s edge. Air in the chamber moves a turbine, producing electricity.

Investor interest in this form of alternative energy was sparked back in the 1970s, when University of Edinburgh scientist Stephen Salter developed a bobbing wave-power generator called “the Duck.” But at the time, the cost of constructing such a generator was prohibitively high (not to mention the expense of connecting the technology to a power grid), and the electronic parts were relatively unsophisticated. In the 1990s, though, a renewed interest in renewable energy, coupled with technological advancements and reduced costs, led to something of a renaissance for wave power. Today, LIMPET and a competing technology, Pelamis, are attracting significant investor attention.

“We think the best thing to do is to start small, get generators up and running,” says David Gibb of Wavegen. So LIMPET is not a money-maker yet — but as far as proof-of-concept is concerned, the turbine is successful. It reliably delivers power to the Scottish national grid, and, despite recent near-hurricane strength storms in the region, LIMPET has never failed. Like its namesake (a limpet is a mollusk that clings to rocks in tidal zones), the generator is holding strong.

The interest in wave technology is also spreading. This year, just off the coast of the Portuguese city Povoa de Varzim, three Pelamis generators are being installed. Each Pelamis (Latin for “sea snake”) consists of a 150-meter-long set of linked, bright-red tubes that resemble tanker train cars. The system floats in the water, perpendicular to the waves, which bend the tubes at their joints and activate hydraulic motors, creating electricity.

The Pelamis’s progenitor, another Scottish company called Ocean Power Delivery, Ltd. (OPD), hopes to start making money right away. It has signed an agreement to sell wave energy to the Portuguese utility company Enersis, and the European Union has promised to buy that power (at an artificially inflated price for now, at least until they perfect the technology enough to bring costs down). “We’re doing this not only because we believe in wave power, but because we think that wave power is going to make money,” says Andrew Scott, the engineer who’s overseeing the Pelamis project for OPD. “Technology will improve, and the price will drop.”

Investors and analysts seem to agree. German utility giant Voith bought Wavegen in May 2005, and General Electric and Merrill Lynch are now investing in OPD. And according to wave-power expert David Jeffrey, these technologies may hold the promise of greater self-sufficiency to remote coastal and island communities around the world.

The United Kingdom, particularly Scotland, has long been a center for wave power. “God has been very generous to Scotland with regard to renewable energy sources,” Salter muses.

But Scotland (and Europe in general) isn’t the only hot spot for ocean-generated electricity: northern Canada, Australia and the northeastern and northwestern coasts of the U.S. are also rich in wave energy because of the wind activity in these temperate zones. Studies commissioned by the city of San Francisco indicate that a wave-power generator is viable there. Under initiatives by Mayor Gavin Newsom, the city is looking seriously at wave energy; Newsom’s office believes there’s enough power offshore to enable San Francisco to shut down the city’s last conventional power plant. “There is an enormous amount of power off the coast of California,” says Jared Blumenfeld, director of San Francisco’s Department of the Environment, “and it’s all untapped.”

Story by Laurel Maury. This article originally appeared in Plenty in October 2006. The story was added to MNN.com in June 2009.